Table 3.
Potential targets for precision modulation of the enteric microbiome of poultry generated from work in conventionally reared and germ-free chickens.
| End point | Microbiome-related plasticity1 |
|---|---|
| Nutrition & Growth | |
| Weight gain and feed conversion efficiency | 9–10% |
| Emulsification and digestion of saturated fat sources | 10% |
| Apparent metabolizable energy | 0.5–0.8 MJ/kg |
| Calcium retention | 5–10% |
| Endogenous nitrogen loss | 3–5% |
| Retention and utilization of nonprotein nitrogen | 8–12% |
| Ammonia excretion | 20–30% |
| Fiber digestion | 30–40% |
| Apparent metabolizable energy of fiber sources | 2–3 MJ/kg of fiber |
| Short-chain fatty acid production in the distal gut | 30–45% |
| Fasting heat production | 20–25% |
| Effect of antinutritional factors2 | 40–50% |
| Amino acid digestibility | 1–2% |
| Fractional protein synthesis rate in tissue | 3–4% |
| Fat and fat-soluble nutrient absorption | 5–10% |
| Efficacy of feed additives3 | Up to 100% |
| Physiology | |
| Pancreatic enzyme persistence in the gut | 7–8% |
| Pancreatic size | 4–5% |
| Liver size | 8–12% |
| Liver fat content | 8–12% |
| Gut mass, especially caudal gut and lamina propria | 20–25% |
| Core body temperature | 0.2–0.4°C |
| Goblet cell number and mucin biosynthesis | 8–10% |
| Mucin composition (sulfation and sialyation) | 50–70% |
| Purine metabolism and renal function | 20–30% |
| Intestinal (nongastric) pH | 0.2–0.3 pH points |
| Spleen development | 20–30% |
| Absorptive area of the small intestine | 80–90% |
| Immunity and Health | |
| Severity of coccidiosis infection4 | 50–100% |
| White blood cell, neutrophil, and lymphocyte counts | 5–15% |
| Gut redox | 20–30% |
| Tight junction integrity | 20–30% |
| Immune tissue maturation rate | 70–90% |
| Liver enzyme function and plasma protein profile | 5–8% |
| Transcription-factor encoding gene expression | 70–90% |
| Neuroactive steroid concentrations in plasma and brain | 80–100% |
| Interferon inducible gene expression | 50–70% |
1
Possible plasticity of selected end point achievable via microbiome modulation based on summary of available literature.
2
For example trypsin inhibitors or viscous nonstarch polysaccharides.
3
Including acids, carbohydrates & prebiotics, salts, nonprotein nitrogen sources, amino acids, and minerals.
4
At time of publication this has only been demonstrated for Eimeria tenella.